Research On Mechanism Of Neurovascular Coupling In Barrel Cortex

With optical imaging of intrinsic signals,this dissertation investigated the spatial and temporal characteristics of low-frequency oscillation(LFO)based on whisker-barrel cortex system.Furthermore,after locating the active region,the mechanism of neurovascular coupling was studied in barrel cortex using simultaneous recording of laser Doppler flowmetry and microelectrode.These researches are important to decipher the relationship between neural activity and hemodynamic response and the underlying operation mechanism of the brain.The main contents and contributions of this dissertation are summarized as follows:The modulation of stimulation to spontaneous LFO with mechanical bending actuators.Spontaneous LFO have been found in cerebral hemodynamics and metabolisms with different techniques and species.In this study,optical imaging system was employed to detect hemodynamic changes in the anesthetized rat cerebral cortex.Under red or green illumination,the phase and amplitude distributions of spontaneous LFOs were investigated before and after single whisker stimulation.Spontaneous LFOs can be modulated by the stimulus,and we found obvious synchronization of phase distributions at around 0.1 Hz in two hemispheres.After stimulus,the amplitude of spontaneous LFOs in the region of arteries was increased under green illumination,while the amplitude of spontaneous LFOs in the region of veins was increased under red illumination.The present study is the first to analyze the spatial-temporal characteristics of LFO with single whisker stimulation.The precise mechanisms and roles of spontaneous LFOs remain unclear.We speculated the extensive synchronization of LFO phases may be associated with the brain function of global alertness and vigilance.The study of spontaneous LFOs also has great significance to that of brain functional connectivity.Research on neurovascular coupling in barrel cortex.We located the active region with optical imaging device.According to the knowledge of spatial distribution of rat brain vasculature,we selected three regions of interest in vein,artery and active region respectively,and calculated the time curve of hemodynamics.Under green illumination,the relative change of local blood volume was much bigger in artery and active region than in vein.Under red illumination,Hbr response to whisker stimulation in artery has the shortest response time and lowest magnitude,while that in vein has the biggest response time and highest magnitude.Furthermore,we found the difference between the center of initial dip and that of rebound fluctuation.The mechanism of neurovascular coupling was studied in barrel cortex using simultaneous recordings of laser Doppler flowmetry and microelectrode.The period of LFP response have high relationship with stimulation frequency.We calculated the pearson correlation coefficient between different neural and hemodynamic variables,found that the relationship between magnitude of CBF response and number of spike burst during stimulation process have high level significance.Moreover,the relative power change of LFP and MUA after stimulation also significantly related to magnitude of CBF response.